150 



MAINE AGRICULTURAL EXPERIMENT STATION. 



PERCEJJTAGES OF IMPURITIES (CARBON, SAND AND SILICA) AND PURE 

 ASH IN THE CRUDE ASH. 







03 









O) 



J 









CO 







'C 



<5 





Sample number. 



S 



« 















P 



3 





, 



" 



Oh 







% 



% 



3045 





9.36 

 12.32 

 5.14 

 7.04 



90.6* 



3047 



87. 6S 



3050 



94. S& 



3051 



92.96 







ANALYSIS OF PURE ASH OF POTATOES. 













o . 













a 



'- ^ 



O j^ 





. 









o~-j, 



-O 





.a 





^ 



03 



^ — 



5» 



Sample number. 







SO 

 35 



S)6 





2-C 





% 



% 



% 



% 



% 



% 



3045 



55.13 



1.70 



1.01 



3.85 



15.78 



6.9a 



3047 



56.16 



1.62 



1.38 



3.93 



14.50 



5.98 



3050 



56.43 

 57.30 



1.70 

 2.15 



1.29 

 1.05 



3.76 

 3.57 



15.00 

 13.33 



6.3S 



3051 



5.56 







RELATION BETWEEN STARCH CONTENT AND SPECIFIC GRAVITY. 



The specific gravity of starch is 1.65, water being taken as 

 one. From this it would seem to follow that the richer a potato 

 is in starch, the higher will be its specific gravity. From this 

 assumption, a German agricultural calendar* has for years pub- 

 lished a table giving the starch content of potatoes correspond- 

 ing to various specific gravities. Assuming this method to be 

 reliable, one of the best experiment stations in the United States 

 has made an otherwise valuable investigation of little account. 

 In Wiley's Principles and Practice of Agricultural Analysis, the 

 unreliability of this method for scientific purposes is pointed out. 

 The figures obtained in the analyses here reported, show in a 

 striking manner the unreliability of the specific gravity method 

 of determining starch in potatoes. In only one instance, (No. 

 3045) is there a practical agreement between the starch deter- 



*Mentzel und v. Lengerke's Landw. Huelfs und Scbreib-Kalender. 



